v4.19.13 snapshot.
diff --git a/arch/arc/include/asm/smp.h b/arch/arc/include/asm/smp.h
new file mode 100644
index 0000000..0861007
--- /dev/null
+++ b/arch/arc/include/asm/smp.h
@@ -0,0 +1,145 @@
+/*
+ * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef __ASM_ARC_SMP_H
+#define __ASM_ARC_SMP_H
+
+#ifdef CONFIG_SMP
+
+#include <linux/types.h>
+#include <linux/init.h>
+#include <linux/threads.h>
+
+#define raw_smp_processor_id() (current_thread_info()->cpu)
+
+/* including cpumask.h leads to cyclic deps hence this Forward declaration */
+struct cpumask;
+
+/*
+ * APIs provided by arch SMP code to generic code
+ */
+extern void arch_send_call_function_single_ipi(int cpu);
+extern void arch_send_call_function_ipi_mask(const struct cpumask *mask);
+
+/*
+ * APIs provided by arch SMP code to rest of arch code
+ */
+extern void __init smp_init_cpus(void);
+extern void first_lines_of_secondary(void);
+extern const char *arc_platform_smp_cpuinfo(void);
+
+/*
+ * API expected BY platform smp code (FROM arch smp code)
+ *
+ * smp_ipi_irq_setup:
+ * Takes @cpu and @hwirq to which the arch-common ISR is hooked up
+ */
+extern int smp_ipi_irq_setup(int cpu, irq_hw_number_t hwirq);
+
+/*
+ * struct plat_smp_ops - SMP callbacks provided by platform to ARC SMP
+ *
+ * @info: SoC SMP specific info for /proc/cpuinfo etc
+ * @init_early_smp: A SMP specific h/w block can init itself
+ * Could be common across platforms so not covered by
+ * mach_desc->init_early()
+ * @init_per_cpu: Called for each core so SMP h/w block driver can do
+ * any needed setup per cpu (e.g. IPI request)
+ * @cpu_kick: For Master to kickstart a cpu (optionally at a PC)
+ * @ipi_send: To send IPI to a @cpu
+ * @ips_clear: To clear IPI received at @irq
+ */
+struct plat_smp_ops {
+ const char *info;
+ void (*init_early_smp)(void);
+ void (*init_per_cpu)(int cpu);
+ void (*cpu_kick)(int cpu, unsigned long pc);
+ void (*ipi_send)(int cpu);
+ void (*ipi_clear)(int irq);
+};
+
+/* TBD: stop exporting it for direct population by platform */
+extern struct plat_smp_ops plat_smp_ops;
+
+#else /* CONFIG_SMP */
+
+static inline void smp_init_cpus(void) {}
+static inline const char *arc_platform_smp_cpuinfo(void)
+{
+ return "";
+}
+
+#endif /* !CONFIG_SMP */
+
+/*
+ * ARC700 doesn't support atomic Read-Modify-Write ops.
+ * Originally Interrupts had to be disabled around code to gaurantee atomicity.
+ * The LLOCK/SCOND insns allow writing interrupt-hassle-free based atomic ops
+ * based on retry-if-irq-in-atomic (with hardware assist).
+ * However despite these, we provide the IRQ disabling variant
+ *
+ * (1) These insn were introduced only in 4.10 release. So for older released
+ * support needed.
+ *
+ * (2) In a SMP setup, the LLOCK/SCOND atomicity across CPUs needs to be
+ * gaurantted by the platform (not something which core handles).
+ * Assuming a platform won't, SMP Linux needs to use spinlocks + local IRQ
+ * disabling for atomicity.
+ *
+ * However exported spinlock API is not usable due to cyclic hdr deps
+ * (even after system.h disintegration upstream)
+ * asm/bitops.h -> linux/spinlock.h -> linux/preempt.h
+ * -> linux/thread_info.h -> linux/bitops.h -> asm/bitops.h
+ *
+ * So the workaround is to use the lowest level arch spinlock API.
+ * The exported spinlock API is smart enough to be NOP for !CONFIG_SMP,
+ * but same is not true for ARCH backend, hence the need for 2 variants
+ */
+#ifndef CONFIG_ARC_HAS_LLSC
+
+#include <linux/irqflags.h>
+#ifdef CONFIG_SMP
+
+#include <asm/spinlock.h>
+
+extern arch_spinlock_t smp_atomic_ops_lock;
+extern arch_spinlock_t smp_bitops_lock;
+
+#define atomic_ops_lock(flags) do { \
+ local_irq_save(flags); \
+ arch_spin_lock(&smp_atomic_ops_lock); \
+} while (0)
+
+#define atomic_ops_unlock(flags) do { \
+ arch_spin_unlock(&smp_atomic_ops_lock); \
+ local_irq_restore(flags); \
+} while (0)
+
+#define bitops_lock(flags) do { \
+ local_irq_save(flags); \
+ arch_spin_lock(&smp_bitops_lock); \
+} while (0)
+
+#define bitops_unlock(flags) do { \
+ arch_spin_unlock(&smp_bitops_lock); \
+ local_irq_restore(flags); \
+} while (0)
+
+#else /* !CONFIG_SMP */
+
+#define atomic_ops_lock(flags) local_irq_save(flags)
+#define atomic_ops_unlock(flags) local_irq_restore(flags)
+
+#define bitops_lock(flags) local_irq_save(flags)
+#define bitops_unlock(flags) local_irq_restore(flags)
+
+#endif /* !CONFIG_SMP */
+
+#endif /* !CONFIG_ARC_HAS_LLSC */
+
+#endif